diff --git a/lib/hooks/input-state-container-hooks.js b/lib/hooks/input-state-container-hooks.js
--- a/lib/hooks/input-state-container-hooks.js
+++ b/lib/hooks/input-state-container-hooks.js
@@ -48,6 +48,13 @@
 } from '../utils/blob-service.js';
 import { useSelector, useDispatch } from '../utils/redux-utils.js';
 
+type MediaIDUpdatePayload = { +id: string, +thumbnailID?: string };
+type MediaIDUpdates = { +[string]: MediaIDUpdatePayload };
+export type SendMultimediaMessagePayload = {
+  +result: SendMessagePayload,
+  +mediaIDUpdates?: MediaIDUpdates,
+};
+
 function useInputStateContainerSendTextMessage(): (
   messageInfo: RawTextMessageInfo,
   threadInfo: ThreadInfo,
@@ -134,7 +141,7 @@
   messageInfo: RawMultimediaMessageInfo,
   sidebarCreation: boolean,
   isLegacy: boolean,
-) => Promise<SendMessagePayload> {
+) => Promise<SendMultimediaMessagePayload> {
   const sendMultimediaMessage = useSendMultimediaMessage();
   const legacySendMultimediaMessage = useLegacySendMultimediaMessage();
   const sendComposableDMOperation = useSendComposableDMOperation();
@@ -160,12 +167,13 @@
       const isThickThread = threadInfo && threadTypeIsThick(threadInfo.type);
 
       if (!isThickThread && isLegacy) {
-        const { messageMedia } = await migrateMessageMediaToKeyserver(
-          messageInfo,
-          reassignThickThreadMedia,
-          dispatch,
-          processHolders,
-        );
+        const { messageMedia, mediaIDUpdates } =
+          await migrateMessageMediaToKeyserver(
+            messageInfo,
+            reassignThickThreadMedia,
+            dispatch,
+            processHolders,
+          );
         const mediaIDs = [];
         for (const { id } of messageMedia) {
           mediaIDs.push(id);
@@ -177,20 +185,24 @@
           sidebarCreation,
         });
         return {
-          localID,
-          serverID: result.id,
-          threadID: messageInfo.threadID,
-          time: result.time,
+          result: {
+            localID,
+            serverID: result.id,
+            threadID: messageInfo.threadID,
+            time: result.time,
+          },
+          mediaIDUpdates,
         };
       }
 
       if (!isThickThread && !isLegacy) {
-        const { messageMedia } = await migrateMessageMediaToKeyserver(
-          messageInfo,
-          reassignThickThreadMedia,
-          dispatch,
-          processHolders,
-        );
+        const { messageMedia, mediaIDUpdates } =
+          await migrateMessageMediaToKeyserver(
+            messageInfo,
+            reassignThickThreadMedia,
+            dispatch,
+            processHolders,
+          );
         const mediaMessageContents =
           getMediaMessageServerDBContentsFromMedia(messageMedia);
         const result = await sendMultimediaMessage({
@@ -200,10 +212,13 @@
           sidebarCreation,
         });
         return {
-          localID,
-          serverID: result.id,
-          threadID: messageInfo.threadID,
-          time: result.time,
+          result: {
+            localID,
+            serverID: result.id,
+            threadID: messageInfo.threadID,
+            time: result.time,
+          },
+          mediaIDUpdates,
         };
       }
 
@@ -238,10 +253,12 @@
         throw e;
       }
       return {
-        localID,
-        serverID: messageID,
-        threadID: messageInfo.threadID,
-        time,
+        result: {
+          localID,
+          serverID: messageID,
+          threadID: messageInfo.threadID,
+          time,
+        },
       };
     },
     [
@@ -260,9 +277,6 @@
   return mediaID.indexOf('|') !== -1;
 }
 
-type MediaIDUpdatePayload = { +id: string, +thumbnailID?: string };
-type MediaIDUpdates = { +[string]: MediaIDUpdatePayload };
-
 async function migrateMessageMediaToKeyserver(
   messageInfo: RawMultimediaMessageInfo,
   reassignMediaMetadata: MediaMetadataReassignmentAction,
diff --git a/native/input/input-state-container.react.js b/native/input/input-state-container.react.js
--- a/native/input/input-state-container.react.js
+++ b/native/input/input-state-container.react.js
@@ -25,6 +25,7 @@
 import commStaffCommunity from 'lib/facts/comm-staff-community.js';
 import { useAllowOlmViaTunnelbrokerForDMs } from 'lib/hooks/flag-hooks.js';
 import {
+  type SendMultimediaMessagePayload,
   useInputStateContainerSendMultimediaMessage,
   useInputStateContainerSendTextMessage,
 } from 'lib/hooks/input-state-container-hooks.js';
@@ -159,7 +160,7 @@
     messageInfo: RawMultimediaMessageInfo,
     sidebarCreation: boolean,
     isLegacy: boolean,
-  ) => Promise<SendMessagePayload>,
+  ) => Promise<SendMultimediaMessagePayload>,
   +sendTextMessage: (
     messageInfo: RawTextMessageInfo,
     threadInfo: ThreadInfo,
@@ -398,7 +399,7 @@
     const sidebarCreation =
       this.pendingSidebarCreationMessageLocalIDs.has(localID);
     try {
-      const result = await this.props.sendMultimediaMessage(
+      const { result } = await this.props.sendMultimediaMessage(
         messageInfo,
         sidebarCreation,
         false,
diff --git a/web/input/input-state-container.react.js b/web/input/input-state-container.react.js
--- a/web/input/input-state-container.react.js
+++ b/web/input/input-state-container.react.js
@@ -35,6 +35,7 @@
 import commStaffCommunity from 'lib/facts/comm-staff-community.js';
 import { useAllowOlmViaTunnelbrokerForDMs } from 'lib/hooks/flag-hooks.js';
 import {
+  type SendMultimediaMessagePayload,
   useInputStateContainerSendMultimediaMessage,
   useInputStateContainerSendTextMessage,
 } from 'lib/hooks/input-state-container-hooks.js';
@@ -154,7 +155,7 @@
     messageInfo: RawMultimediaMessageInfo,
     sidebarCreation: boolean,
     isLegacy: boolean,
-  ) => Promise<SendMessagePayload>,
+  ) => Promise<SendMultimediaMessagePayload>,
   +sendTextMessage: (
     messageInfo: RawTextMessageInfo,
     threadInfo: ThreadInfo,
@@ -553,7 +554,7 @@
     const sidebarCreation =
       this.pendingSidebarCreationMessageLocalIDs.has(localID);
     try {
-      const result = await this.props.sendMultimediaMessage(
+      const { result } = await this.props.sendMultimediaMessage(
         messageInfo,
         sidebarCreation,
         true,